It is obviously extremely hard to pin down a solid figure for how many people are going to be displaced due to the challenges posed by a warming planet. But virtually every publication I have read on the challenges of global warming rank the issue of “climate refugees” as both a serious political and economic problem. Here is an old estimate of the number of climate refugees, and it seems pretty well within what other places are saying. Here it is argued that agricultural dislocation, sea-level rise, flooding, droughts and disruptions of traditional weather patterns may cause as many as 200 million people to be at risk for displacement.

Take that number seriously and at face value. I have no reason not to believe it. The linked to paper says that:

these findings are based on an 18-month research project carried out in consultation with representatives of governments, intergovernmental bodies, United Nations agencies, the World Bank and dozens of NGOs, including refugee organizations. The findings also reflect a broad spectrum of expert opinion on the part of leading scientists and policy analysts in all major parts of the world. In particular, the research report draws heavily on the experience of field workers with their extensive and first-hand knowledge. Further, the overall assessment is illustrated by six regional case studies with detailed documentation. All the individual findings and conclusions are supported by specific references, more than 1,000 of which can be found in the main text.

The above report itself was funded by the UN Population Fund, the US Government and the Rockefeller Foundation. That is good information for those of you thinking I may be pulling data from some sort of nefarious and disrespectful source. Of particular concern when it comes to global warming damages and costs is that they do not fall proportionately on the world and certainly not proportionate to income or on those who generated much of the warming. Put simply, the rich Northern countries created it, and the poorer Global South is eating it.That is one major reason why making progress on climate change is hard.

Now, if you look for what the estimated financial costs of these dislocations will be over time, you are going to have a very hard time finding them. So, to make it easy, let us suppose that the entire annual cost of global warming is going to come from the climate refugee problem. Remember, the argument is that poor people are being uprooted from their lifestyles that were happening near oceans, rivers and vulnerable farm and weather systems. It is also very clear that these areas and people are very poor and may in fact be very costly to develop climate resilience for. Suppose global GDP is $100 trillion at the moment. Reasonable estimates of the annual cost of climate change if nothing at all is done are likely to come in the 1% of global GDP range. But let’s double it for the sake of conservatism. And, let’s assume that all of these costs are due to refugees. This would mean that a climate refugee crisis would lead to a $2 trillion per year global cost. Note that in many, many ways this is a vast overstatement of what the actual cost would be (I know, it can precipitate nuclear war and then we are in Talebian “blow-up” world). Why? Well, not alll of the costs from AGW are going to come from refugees … and two, while the refugee crisis is not just a one-time change, it also can’t be an ongoing change. Once every last climate victim is moved, there will be fewer remaining victims. But ignore all of that.

What is the point of all of this? So, climate refugees are going to be a big cost.

There is also extremely strong research (no less authoritative on the refugee numbers above) that shows that there are tremendous gains to migrants when they move from poor countries to rich countries. Indeed, even under very modest assumptions about the changes to open-borders policies, economists have estimated that the total gains to world well being from migration would absolutely swamp any cost that you can come up with from the costs of refugees. Here is perhaps the most famous paper, but there are many more. One of the paper’s findings is that,

If half the population of the poor region emigrates, migrants would gain $23 trillion—which is 38 percent of global GDP. For nonmigrants, the outcome of such a wave of migration would have complicated effects: presumably, average wages would rise in the poor region and fall in the rich region, while returns to capital rise in the rich region and fall in the poor region. The net effect of these other changes could theoretically be negative, zero, or positive. But when combining these factors with the gains to migrants, we might plausibly imagine overall gains of 20–60 percent of global GDP.

Let’s get our heads around this. The MORE migrants that global warming creates, the greater the potential wealth will be created from those migrations. Indeed the very core of the global warming migration worry is that the people migrating are among the poorest and least fortunate people. If that is the case, these migrants MUST be making their way into richer countries. For sure, the dislocations and the political issues are extraordinarily challenging and costly. But given the size of the gains. it would seem to me, much like people like to see “silver linings” when lightning burns their old house down, that indeed moving people, even if not by choice, to richer countries because of climate change, is likely to make the world better off by something close to $40 trillion per year.

I would make two points. First, it is hard to argue that these dislocations would be entirely unwelcome among those migrating. Why? They are really prevented from freely migrating today! I am sure some percentage of the world’s poor would very gladly go to Canada or Norway or some such place if they had the chance. Global warming may just force that outcome. Second, while the costs of these great migrations are likely to be transitory, these gains from “forced open borders” would seem to be longer-lasting, if not permanent. So, we are looking at a permanent increase in GDP that is at least twenty times larger than the transitory costs imposed on the world by the forced Global Warming migrations.

You can talk these benefits down from $40 trillion for sure, and the magnitude of them is seriously a function of many policies choices and institutions in the wealthier world, but it is really hard to imagine you can get those benefits down anywhere near that $2 trillion cost, which itself is exaggerated for the purposes of this post.

I am not saying we should all pray for sea level rise and mass dislocation due to warming, particularly since unknown positive feedbacks can certainly push global warming into existential threat territory. On the other hand, if we want to put blinders on and throw out the worst case scenarios, along with the other benefits a warmer world may bring (along with the costs), it would appear to be that Global Warming may in fact be one of the greatest gifts we have ever given to humanity, behind sliced bread of course.